bone tissue & joints

Inorganic salts

(inorganic matrix) mostly calcium phosphate & calcium carbonate deposited along collagen fibers

diaphysis

(long bone) contains an extended tubular shaft called diaphysis

epiphysis

(long bone) found on each end of diaphysis

osteoid

(organic matrix) contains collagen fibers embedded in ground substance

Parts of a Long Bone

1. An expanded end of a long bone is an epiphysis. 2. An epiphysis articulates with another bone. 3. Articular cartilage is located on an epiphysis. 4. The shaft of a long bone is called a diaphysis. 5. Periosteum is a tough, vascular, fibrous membrane covering the diaphysis of a bone. 6. Periosteum functions to form and repair bone tissue. 7. Processes provide sites for attachments of tendons or ligaments. 8. The wall of the diaphysis is composed of compact bone. 9. Compact bone has a continuous matrix with no gaps. 10. The epiphyses are largely composed of spongy bone bone. 11. Spongy bone consists of bony plates called trabeculae. 12. A bone usually has both compact bone and spongy bone. 13. A canal called the medullary cavity runs through the diaphysis. 14. Endosteum lines the medullary cavity and spaces of spongy bone. 15. Endosteum contains bone-forming cells. 16. The tissue that fills the spaces of bone is called marrow. 17. The two forms of marrow are red and yellow.

Bone Function A. Support and Protection

1. Bones give shape to structures such as the head, face, thorax, and limbs. 2. The bones of lower limbs, pelvis, and vertebral column support the body's weight. 3. The bones of the skull protect the eyes, ears, and brain. 4. The bones of the thorax protect the heart and lungs. 5. Bones of the pelvic girdle protect lower abdominal and internal reproductive organs.

Intramembranous Bones

1. Examples of intramembranous bones are flat bones of the skull. 2. Osteogenesis is bone development. 3. During their development, membranelike layers of primitive connective tissue appear at the sites of their future bones. 4. Networks of blood vessels supply the connective tissue layers. 5. Osteoblasts are bone-forming cells. 6. Osteoblasts deposit bony matrix around themselves. 7. Spongy bone can become compact bone as spaces fill with bone matrix. 8. As development continues, osteoblasts may become surrounded by matrix. 9. Matrix surrounding the processes of osteoblasts gives rise to canaliculi. 10. Once isolated, osteoblasts become osteocytes. 11. Periosteum comes from cells of the primitive connective tissue that persist outside of the developing bone. 12. Compact bone is formed by osteoblasts on the inside of periosteum. 13. Intramembranous ossification is the process of replacing connective tissue to form an intramembranous bone.

Factors Affecting Bone Development, Growth, and Repair

1. Factors that affect bone development, growth and repair include nutrition, exposure to sunlight, hormonal secretions, and physical exercise. 2. Vitamin D is necessary for calcium absorption. 3. Lack of vitamin D can lead to the diseases rickets and osteomalacia. 4. Vitamin A is necessary for osteoblast and osteoclast activity during normal development. 5. Vitamin C is required for collagen synthesis. 6. Growth hormone stimulates division of cartilage cells in epiphyseal plates. 7. In children, the absence of growth hormone leads to pituitary dwarfism. 8. An excess of growth hormone before the epiphyseal plates ossify leads to pituitary gigantism. 9. In adults, an excess of growth hormone leads to acromegaly. 10. Thyroid hormone can halt bone growth by causing premature ossification of the epiphyseal plates. 11. Deficiency of thyroid hormone may stunt growth. 12. Parathyroid hormone stimulates an increase in the number and activity of osteoclasts. 13. Androgens are male sex hormones. 14. Androgens promote formation of bone tissue. 15. Sex hormones also stimulate ossification of the epiphyseal plates. 16. Females typically reach their maximum heights earlier than males because the effects of estrogen on the epiphyseal plates are stronger than androgens. 17. Physical stress stimulates bone growth.

TYPES OF JOINT MOVEMENTS

1. Gliding movements = when flat bone surfaces glide or slide over one another. a. occur at cartilaginous joints; b. Examples = intervertebral discs and sternoclavicular joints. 2. Angular movements = changes in angles between bones; occur only at synovial joints. a. Flexion = decreasing the angle between 2 bones. Example = head toward chest. 1. Dorsiflexion = bringing foot closer to shin. 2. Plantar flexion = pointing one's toe (flexion toward the sole). b. Extension = increasing the angle between 2 bones. Example = straightening a flexed neck. 1. Hyperextension = increasing the angle greater than 180o; See Figure 8.10, page 261. V. TYPES OF JOINT MOVEMENTS: B. Three general types of movement: (continued) 2. Angular Movements of Synovial Joints (continued) c. Abduction = moving a limb away from the midline. Example = raising arm or thigh laterally; d. Adduction = moving a limb toward the midline. See Fig 8.10, page 261 to see the above examples. e. Circumduction = moving a limb in a circular (cone-shaped) manner. f. Rotation = turning movement of a bone along its long axis. Example = atlas over axis (i.e. "just say no"). Example = shoulder and hip joint. See Fig 8.11, page 262 to see the above examples.

Growth at the Epiphyseal Plate

1. In a long bone, the diaphysis is separated from the epiphysis by an epiphyseal plate. 2. The cartilaginous cells occur in four layers. 3. The first layer is composed of resting cells that do not actively participate in growth. 4. The first layer anchors the epiphyseal plate to the bony tissue of the epiphysis. 5. The second layer contains rows of many young cells undergoing mitosis. 6. As new cells appear, the cartilaginous plate thickens. 7. The third layer is formed by older cells that are left behind as new cells appear. 8. The cells of the third layer enlarge and thicken the epiphyseal plate. 9. The fourth layer is composed of dead cells and calcified intercellular substance. 10. Osteoclasts break down calcified matrix of bone. 11. Osteoclasts originate from monocytes. 12. Osteoclasts secrete acids that dissolve the inorganic component of the calcified matrix, and their lysosomal enzymes digest the organic components. 13. Osteoclasts phagocytize components of the bony matrix. 14. After osteoclasts remove the matrix, osteoblasts invade the region and deposit bone tissue in place of calcified matrix. 15. A long bone continues to lengthen while the cartilaginous cells of the epiphyseal plates are active. 16. Lengthening of the bone is no longer possible when once the ossification centers of the diaphysis and epiphysis meet and the epiphyseal plates ossify. 17. The medullary cavity forms when osteoclasts erode bone tissue in the diaphysis. 18. The bone in the central regions of the epiphyses and diaphysis remains spongy. 19. Hyaline cartilage on the ends persists as articular cartilage.

bone function - Inorganic Salt Storage

1. Intercellular matrix of bone tissue contains collagen and inorganic mineral salts. 2. The salts account for about 70% by weight. 3. Hydroxyapatites are tiny crystals of calcium phosphate. 4. The body requires calcium for many metabolic processes including blood clot formation, nerve impulse conduction, and muscle cell contraction. 5. When blood calcium is low, parathyroid hormone stimulates osteoclasts to break down bone tissue to release calcium salts. 6. Very high blood calcium levels inhibit osteoclast activity. 7. Calcitonin stimulates osteoblasts to form bones. 8. Bone tissue contains lesser amounts of magnesium, sodium, potassium and carbonate ions.

Endochondral Bones

1. Most of the bones of the skeleton are endochondral bones. 2. Endochondral bones develop as masses of hyaline cartilage. 3. Eventually the cartilage decomposes. 4. As the cartilage decomposes, a periosteum forms from connective tissue that encircles the developing structure. 5. Blood vessels and undifferentiated connective tissue cells invade the disintegrating tissue. 6. Some of the cells differentiate into osteoblasts. 7. Osteoblasts form spongy bone in the spaces previously housed by cartilage. 8. Endochondral ossification is the process of forming an endochondral bone by the replacement of hyaline cartilage. 9. The primary ossification center is an area in the diaphysis of a long bone in which the bony tissues begin to replace hyaline cartilage. 10. Secondary ossification centers appear in epiphyses. 11. The epiphyseal plate is a band of cartilage between the primary and secondary ossification centers.

Endochondral Bones

1. Most of the bones of the skeleton are endochondral bones. 2. Endochondral bones develop as masses of hyaline cartilage. 3. Eventually the cartilage decomposes. 4. As the cartilage decomposes, a periosteum forms from connective tissue that encircles the developing structure. 5. Blood vessels and undifferentiated connective tissue cells invade the disintegrating tissue. 6. Some of the cells differentiate into osteoblasts. 7. Osteoblasts form spongy bone in the spaces previously housed by cartilage. 8. Endochondral ossification is the process of forming an endochondral bone by the replacement of hyaline cartilage. 9. The primary ossification center is an area in the diaphysis of a long bone in which the bony tissues begin to replace hyaline cartilage. 10. Secondary ossification centers appear in epiphyses. 11. The epiphyseal plate is a band of cartilage between the primary and secondary ossification centers.

Bone Development and Growth

1. Parts of the skeleton begin to form during the first few weeks of prenatal development. 2. Bony structures continue to grow until adulthood. 3. Bones form by replacing existing connective tissues. 4. Intramembranous bones originate within sheetlike layers of connective tissue. 5. Endochondral bones originate within cartilage

Bone Development and Growth

1. Parts of the skeleton begin to form during the first few weeks of prenatal development. 2. Bony structures continue to grow until adulthood. 3. Bones form by replacing existing connective tissues. 4. Intramembranous bones originate within sheetlike layers of connective tissue. 5. Endochondral bones originate within cartilage.

Bone Classification

1. The four classes of bone according to shape are long, short, flat, and irregular. 2. Examples of long bones are forearm and thigh bones. 3. Short bones are shaped like cubes. 4. Examples of short bones are wrist bones and ankle bones. 5. Flat bones are platelike structures. 6. Examples of flat bones are some skull bones, ribs, and scapulae. 7. Irregular bones have a variety of shapes. 8. Examples of irregular bones are vertebrae and some facial bones. 9. Round bones are also called sesamoid bones. 10. Sesamoid bones are small and nodular and embedded in tendons. 11. An example of a sesamoid bone is the patella.

Homeostasis of Bone Tissue

1. Throughout life, osteoclasts resorb bone tissue and osteoblasts replace bone. 2. About 3% to 5% of bone calcium is exchanged each year.

functions of bone

1. support 2. storage of minerals & lipids 3. blood cell production 4. protection 5. leverage

Life-Span Changes

A. An incremental decrease in height begins at about age 30. B. Compression fractures of the vertebrae may contribute to loss of height. C. As calcium levels fall, bones become brittle and prone to fracture. D. Gradually, osteoclasts come to outnumber osteoblasts. E. By age 35 all adults start to lose bone mass. F. Trabecular bone shows signs of aging first. G. Compact bone loss begins around the age of 40. H. In the first decade following menopause 15 to 20% of trabecular bone is lost and 10 to 15% of compact bone is lost in women. I. The most common fractures in the elderly are vertebral compression fractures, hip fractures, wrist fractures, leg fractures, and pelvis fractures. J. Preserving skeletal health may involve avoiding falls, taking calcium supplements, getting enough vitamin D, avoiding carbonated beverages, and getting regular exercise.

GENERAL STRUCTURE OF A SYNOVIAL JOINT

A. Articular cartilage = hyaline cartilage covers the surface of each bone; B. Joint cavity = a potential space between the two bones, filled with synovial fluid; C. Articular capsule = double layered capsule surrounding cavity: 1. External, tough flexible fibrous capsule (continuous with periosteum of the bones); 2. Synovial membrane = loose CT lining of fibrous capsule, that also covers all internal joint surfaces excluding hyaline cartilage; D. Synovial fluid = viscous lubricating fluid within cavity. 1. reduces friction between cartilages of 2 bones; 2. provide "weeping lubrication"; 3. nourish cartilage; 4. contain phagocytes. E. Reinforcing ligaments = ligaments that strengthen joint. 1. Definition: A ligament joins a bone to another bone across a synovial joint. 2. usually thickened portions of fibrous capsule (intrinsic or capsular); F. Other joint features: See Fig 8.8, page 258. 1. fatty pads (hip & knee); 2. menisci or articular discs or that separate cavity into 2 compartments (knee, jaw, sternoclavicular). 3. bursa = flattened fibrous sacs with a synovial membrane and fluid that act as "ball bearings" to prevent friction on adjacent structures during joint activity; a. cushion the movement of one body part over another; b. located between skin and bone (where skin rubs over bone), and between muscle, tendons, ligaments and bone.

TYPES OF SYNOVIAL JOINTS

A. Ball-and-socket joints = most freely movable joints; all angular movement; 1. The head of one bone fits into the socket of another; 2. Examples = hip and shoulder. B. Condyloid joints = permit all angular motion, except rotation. Examples = wrists and knuckles, C. Gliding joints = cartilaginous joints; Example = intervertebral discs. D. Hinge joints = permit flexion & extension only; Examples = elbow and knee. E. Pivot joints = permit rotation; Example = first intervertebral joint (atlantoaxial joint) F. Saddle joints = thumb;

Fetal Embryonic Development

ALL connective tissue comes from mesenchymal cells These mesenchymal cells differentiate into: Membranes - periosteum Osteoprogenitor cells Osteoprogenitor cells are mitotically active and can differentiate into osteoblast (bone forming cells)

Endosteum

An incomplete cellular layer: lines the marrow cavity covers trabeculae of spongy bone lines central canals Contains osteoblasts, osteoprogenitor cells, and osteoclasts Is active in bone growth and repair

skeletal system

Bones of the skeleton Cartilages, ligaments, tendons and other connective tissues that stabilize and connect bones/joints

storage of minerals & lipids (function)

Ca2+, PO4-, yellow bone marrow/fat (energy)

Cartilaginous Joints

Cartilaginous Joints = joints composed of cartilage; no joint cavity; 2 types: a. Synchondrosis = a plate of hyaline cartilage; sites of bone growth during youth; eventually ossify = synarthrotic; Examples joint between the first rib and manubrium (See Fig 8.5, page 256) and the epiphyseal plate. b. Symphysis = pad or plate of fibrocartilage; compressible "shock absorber"; limited movement = amphiarthroses; Examples intervertebral discs and symphysis pubis. See Fig 8.6, page 256.

Bone Coverings

Covered (outside) by periosteum Lined(inside) by endosteum

Fibrous Joints

Fibrous Joints = joints composed of fibrous tissue; no joint cavity is present; 3 types: a. Sutures = short fibrous CT fibers; See Fig 8.2 and Fig 8.3, page 255. synarthroses. Only found in skull b. Syndesmosis = cord of fibrous tissue called a ligament; amphiarthroses with "give" but no true movement; Example = distal tibiofibular joint. See Fig 8.1, page 254. c. Gomphosis = tooth within its bony socket; (alveolar fossa) short periodontal ligament. See Fig 8.4, page 256.

Functional Classification of Joints:

Functional Classification of Joints: A. Based on the amount of movement allowed. B. 3 types: 1. Synarthroses = immovable joints. a. Example = sutures of skull. 2. Amphiarthroses = slightly movable joints. a. Example = intervertebral discs between vertebrae. 3. Diarthroses = freely movable joints. a. Examples = joints of appendicular skeleton.

Functions of Periosteum

Isolate bone from surrounding tissues Provide a route for circulatory and nervous supply Participate in bone growth and repair

Bone shape

Long Flat Short Irregular Sesamoid Sutural

Endochondral Ossification

Most of the bones in the body are not flat but are formed from a hyaline cartilage(mesenchymal) model which is gradually replaced by bone Interstitial growth - increasing bone length Appositional growth increases bone diameter Timing of epiphyseal closure (growth cessation) differs

Intramembranous Ossification

Starts around the fifth week of development and ends around 2 y/o Direct bone formation - on or within connective tissue memebrane Begins with osteoblast differentiation at ossification center Dermal bones produced E.g., flat bones of skull, mandible, clavicle

Structural Classification of Joints:

Structural Classification of Joints: A. Based on material, which joins bones (between bones). B. 3 types: Fibrous, Cartilaginous, Synovial

Synovial Joints

Synovial Joints = fluid-filled joint cavity; free movement = diarthrosis;

Compact Bones

a. An osteon is a cylinder-shaped unit of compact bone. b. The substance of compact bone is formed from many osteons cemented together. c. Each central canal contains blood vessels and nerves. d. Perforating canals connect osteons. e. Perforating canals contain larger blood vessels and nerves.

Microscopic Structure of bones

a. Bone cells are called osteocytes. b. Lacunae are tiny, chambers that contain osteocytes. c. Lacunae form concentric canals around central canals. d. Osteoctyes transport nutrients and wastes to and from nearby cells. e. Cellular processes of osteocytes pass through canaliculi. f. The intercellular matrix of bone is composed of collagen and inorganic salts.

Spongy Bone

a. Spongy bone is also composed of osteocytes and intercellular material. b. Unlike compact bone, the bone cells do not aggregate around central canals. c. Instead the cells lie within trabeculae. d. Osteocytes get nutrients from substances diffusing into canaliculi that lead to the surface of trabeculae.

Special Movements

a. supination/pronation = movements between the radius and ulna at the proximal radioulnar joint thumb up = supination; thumb down = pronation; b. inversion/eversion = movement of foot; sole inward = inversion; sole out = eversion; c. elevation/depression: shoulder shrug = elevation; mandible in opening mouth = depression. d. protraction/retraction: thrust forward = protraction pull back = retraction

The movement called _____ will move an appendage towards the midline of the body

adduction

Joints that have some limited degree of movement are called _____.

amphiarthrotic

Which of the following does not belong with the others? A) synovial B) diarthrotic C) ball-and-socket D) amphiarthrotic

amphiarthrotic

An _____ is a condition of abnormal stiffness or fusion of bones at a joint.

ankylosis

The _____ is a band that encircles the head of the radius

annular ligament

leverage

articulations w/ muscles contract and cause movement

lacuna

as lamella buids up, osteoblasts become trapped between lamellae. As a result the osteoblast resides within a small cavity called lacuna between lamella.

The hip is an example of a _____ joint

ball-and-socket

The shoulder is an example of a _____ joint.

ball-and-socket

Intramembranous ossification

begins when osteoblasts differentiate within a mesenchymal or fibrous connective tissue. AKA dermal ossification-occures in deeper layers of the dermis

The condition called _____ involves inflammation of a fluid filled sac outside of a joint.

bursitis

The articular processes of the vertebrae and _____ contain gliding joints

carpals

canaliculi

channels radiating out from the lacunae communicate w/ adjacent osteocytes or surrounding blood supply necessary for nutrition of osteocytes since nutrients diffuse to the osteocytes by canaliculi

The best movement that describes throwing a baseball is probably _____ of the arm.

circumduction

irregular bones

complex shapes spinal column, pelvis, several bones in skull

The joint between the phalanges and metacarpals is a _____ joint.

condyloid

Spongy bone (cancellous) (Structure of Bone)

consist of an open network of struts and plates that resembles latticework

Ossification

converting other tissue to bone 2 types Intramembranous Endochondral

protection (function)

covers organs

The ligaments that form a cross at the knee are called _____.

cruciate

Calcification

depositing calcium salts (hydroxyapatite) within tissues during ossification

Closing the jaw is an example of _____ movement.

elevation

long bones

elongated consist of shaft (diaphysis) with 2 ends (epiphysis) that are wider then the shaft

Which of the following is not possible at the shoulder? A) extension B) rotation C) eversion D) circumduction

eversion

When one is standing erect, most of the joints are in the _____ position.

extended

The type of joint between the fetal frontal and parietal bones is classified as a _____ joint.

fibrous

The _____ ligament attaches the lateral condyle of the femur to the head of the fibula.

fibular collateral

The movement that decreases the angle between two bones is called _____.

flexion

osteocyte

formed when osteoblasts stop secreting osteoid and become mature bone cells

Which fibrocartilage ligament encircles the margin of the glenoid cavity of the scapula?

glenoidal labrum

blood cell production (function)

hemopoiesis in red bone marrow

The elbow and phalanges contain _____ joints.

hinge

The articular ends of long bones contain a type of _____ tissue

hyaline cartilage

The term that describes the presence of fluid in a joint, is _____.

hydrarthrosis

Bending the head to observe an airplane will probably cause _____ of the neck.

hyperextension

spongy bone

is found beneath compact bone, fills inner portions of flat bone, and the ends of the long bones in the body porous & lattice-like arrangement of bony spicules

Menisci are extra pieces of fibrocartilage that provide an extra cushion within the _____ joint.

knee

The largest and most complex joint is the _____.

knee

bone function- Blood Cell Formationone functio

l Formation 1. Hematopoiesis is blood cell formation. 2. Blood cell formation begins in the yolk sac. 3. Later in development, blood cells are made in the liver, the spleen, and red bone marrow. 4. Marrow is a soft, netlike mass of connective tissue within the medullary cavities of bond bones, in the irregular spaces of spongy bone, and in the larger central canals of compact bone tissue. 5. Red marrow functions in the formation of red blood cells, white blood cells, and platelets. 6. Red marrow occupies the cavities of most bones in an infant. 7. With increasing age, yellow marrow replaces red marrow. 8. Yellow marrow stores fat. 9. In an adult, red marrow is primarily found in the spongy bone of the skull, ribs, sternum, clavicles, vertebrae, and pelvis.

lamella

layers of osteoid build-up

The strongest and most inflexible part of a synovial joint is the ______.

ligament

The term _____ refers to dislocation of a joint.

luxation

mineralized matrix

most rigid of all connective tissue

osteoclasts

multinucleated located in both inner and outer surfaces of bone actively breakdown bone

What is the main factor that holds the arm to the trunk?

muscles and tendons

Standing on one's toes is an example of _____ of the foot

plantar flexion

Moving the shoulder forward in a straight plane direction is an example of _____.

protraction

support (function)

provide framework

Compact bone (dense) (Structure of Bone)

relatively solid protects marrow cavity

decalcification

remove inorganic salts, so all you see are the cells and organic matrix

The condition of _____ is an autoimmune disease that causes the formation of a joint pannus

rheumatoid arthritis

Turning a doorknob is an example of _____.

rotation

Turning the head on a central axis plane is an example of _____.

rotation

The rotator cuff is a special arrangement of tissues found in the _____.

shoulder

Which of the following is probably the easiest to dislocate? A) knee B) wrist C) elbow D) shoulder

shoulder

Joint (articulation)

site where two bones come together.

short bone

small, boxy, equal dimensoins carpals & tarsals

sutural bones

small, flat, irregulary shaped between flat bones of skull

sesamoid bone

small, flat, sesame seed shape (patella)

Which of the following has the greatest range of motion?

spheroidal

When standing in the anatomical position, the hands are considered to be in a _____ position

supine

The parietal and temporal bones are joined by a _____.

suture Some of the same type of fibrous membrane as in the fetal skull remain throughout life as the fibrous tissue in the sutures.

The two pubic bones are held together on the anterior surface by a _____ joint.

symphysis

What type of joint is between the bodies of the vertebrae?

symphysis The intervertebral disks are rings of hyaline cartilage that are attached by bands of fibrocartilage, and are symphyses; they act as cushions as well as provide some movement.

The special joint between the distal ends of the tibia and fibula is called a _____.

syndesmosis

Which of the following joints are the most complex?

synovial Synovial joints are complex and have ligaments, a joint capsule and a synovial membrane, as well as other structures.

The bursae resemble _____ in structure and are found around certain joints.

synovial membranes

osteoblasts

these cells are immature bone cells secrete bone matrix lay down layers of osteoid

flat bones

thin, flattened shape roof of skull, sternum, ribs, scapulae

Where is a saddle joint found?

thumb base

Which of the following is an example of a gomphosis?

tooth-alveolus

Endochondral (intracartilaginous) ossification

when developmental cartilage (hyaline cartilage) gradually is replaced by bone.

metaphysis

where epiphysis connects to diaphysis

Compact bone located

where stresses are limited in direction

Spongy bone located

where stresses are weaker or multi-directional